https://orcid.org/0000-0002-1948-8785
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ABSTRACT
The present work experimentally analyzes the performance of a novel waste hot water fed (WHWF) still for potable water production. In contrast to conventional solar stills, in this still hot water flows over the basin and the mass flow rate of water has been utilized to rotate four small alphabet S-shaped rotors provided at the basin. This rotation induces the stirring turbulence in hot water to enhance the evaporation rate. The non-dependency on solar energy provides the characteristic of continuous (both day and night) water production in all weathers. The variation in thermo-exergic and economic parameters has been studied for varying room temperature in the range of 22–30°C and mass flow rate of hot water in range 150–50 kg/h. The cumulative yield at 22°C is 8–21% and at water mass flow rate of 50 kg/h it is about 7–13% more in comparison of other considered room temperature and mass flow rate values. The improvement in exergy efficiency up to 45.7% is observed in the study. The average cost of potable water is Rs 0.92 (0.012 $) and average payback period is 0.9 year for the WHWF still.
Disclosure statement
No potential conflict of interest was reported by the authors.
Nomenclature
| Ec | = | Energy fractions due to convective heat transfer |
| Ee | = | Energy fractions due to evaporative heat transfer |
| Er | = | Energy fractions due to radiative heat transfer |
| Ein | = | Embodied energy (kWh) |
| Eo | = | Annual energy output (kWh) |
| hr | = | Evaporative heat transfer coefficient from water surface to the glass cover (W/m2-oC) |
| hr | = | Radiative heat transfer coefficient from water surface to the glass cover (W/m2-oC) |
| L | = | Latent heat transfer of vaporization (kJ/kg) |
| mf | = | Yield (kg/s) |
| mfy | = | Yearly yield (kg) |
| mw | = | Mass flow rate of hot water (kg/hr) |
| n | = | Product life-cycle |
| Pw | = | Partial pressure of water vapor at water temperature (Pa) |
| Pc | = | Partial pressure of water vapor at glass temperature (Pa) |
| QT | = | Total rate of heat transfer from the water surface to condensing cover (W/m2) |
| Qc_w/c | = | Rate of convective heat transfer (W/m2) |
| Qe_w/c | = | Rate of evaporative heat transfer (W/m2) |
| Qr_w/c | = | Rate of Radiative heat transfer (W/m2-oC) |
| r | = | Annual interest rate |
| Tc | = | Glass temperature (oC) |
| To | = | Room temperature (oC) |
| Tw | = | Water temperature (oC) |
| Xfuel | = | Exergy of fuel |
| Xpump | = | Exergy of pump |
| Xsun | = | Exergy of sun |
| σ | = | Stefan Boltzmann constant |
| ε | = | effective emissivity |
| ηex | = | Exergy efficiency |
| A.C. | = | Annual cost |
| A.A.T.C | = | Annual actual total cost |
| A. O. M.C. | = | Annual maintenance and operating cost |
| A.S.V. | = | Annual salvage value |
| C.O.P.W. | = | Cost of potable water |
| C.R.F | = | Capital Recovery Factor |
| FRP | = | Fiber Reinforced Plastic |
| S.P. | = | Selling price |
| T.I.C | = | Total Investment Cost |
| WHWF | = | waste hot water fed |